Method and circuit for providing an optically coupled linear isolator

Claim 2

An optically coupled linear isolator comprising, first and second light generating means responsive to electrical signals for transmitting proportional signals of light radiation, first and second light responsive means being electrically isolated from respective ones of said light generating means and responsive to said light radiation signals for providing proportional electrical signal outputs, said first and second light responsive means being electrically coupled, detector means fo detecting differences in electrical signal outputs of said first and second light responsive means and providing an output difference signal, circuit means for providing an output voltage proportional to the electrical signals applied to said second light generating means, and said circuit means including means for impressing said difference signal across said second light generating means balancing said electrical signal outputs of said light responsive means and making said output voltage proportional to the electrical signals applied to said first light generating means.

Claim 3

An optically coupled linear isolator as claimed in claim 1 in which, said first and second light responsive means having a response characteristic that is linear over a portion thereof, and means for applying electrical signals to said light generating means in said linear characteristic portion.

Claim 4

An optically coupled linear isolator as claimed in claim 2 in which, said first and second light generating means comprising light emitting diodes.

Claim 5

An optically coupled linear isolator as claimed in claim 3 in which, said first and second light responsive means comprising light responsive transistors.

Claim 6

An optically coupled linear isolator as claimed in claim 4 in which, said first light emitting diode and said first light responsive transistor and said second light emitting diode and said second light emitting transistor being respectively grouped in electrically isolated housings.

Claim 7

An optically coupled linear isolator comprising: first and second light generating means responsive to electrical signals for transmitting proportional signals of light radiation, first and second light responsive means being electrically isolated from respective ones of said light generating means and responsive to said light radiation signals for providing proportional electrical signal outputs, said first and second light responsive means being electrically coupled, detector means for detecting differences in electrical signal outputs of said first and second light responsive means and providing an output difference signal, circuit means for providing an output voltage proportional to the electrical signals applied to said second light generating means, said circuit means including means for impressing said difference signal across said second light generating means balancing said electrical signal outputs of said light responsive means and making said output voltage proportional to the electrical signals applied to said first light generating means, an input electrical signal being fed through a first resistor to an amplifier which amplifier is connected to a source of battery power, and said amplifier feeding the amplified electrical signal to said first light generating means which is a light emitting diode, whereby the current applied to said first light emitting diode is the same current as the current through said resistor.

Claim 8

An optically coupled linear isolator comprising: first and second light generating means responsive to electrical signals for transmitting proportional signals of light radiation, first and second light responsive means being electrically isolated from respective ones of said light generating means and responsive to said light radiation signals for providing proportional electrical signal outputs, said first and second light responsive means being electrically coupled, detector means for detecting differences in electrical signal outputs of said first and second light responsive means and providing an output difference signal, circuit means for providing an output voltage proportional to the electrical signals applied to said second light generating means, said circuit means including means for impressing said difference signal across said second light generating means balancing said electrical signal outputs of said light responsive means and making said output voltage proportional to the electrical signals applied to said first light generating means, an input electrical signal being fed through a first resistor to an amplifier which amplifier is connected to a source of battery power, and said amplifier feeding the amplified electrical signal to said first light generating means which is a light emitting diode, whereby the current applied to said first light emitting diode is the same current as the current through said resistor.

Claim 9

An optically coupled linear isolator as claimed in claim 6 in which, said detector means comprises an amplifier that is responsive to the outputs of each of said first and second light responsive means, which comprise light responsive transistors, a second resistor connected to the output of said amplifier for feeding a voltage to a third amplifier, said third amplifier being powered by a power supply reference to earth ground, said third amplifier feeding a signal to said second light generating means, which comprises a second light emitting diode, said output of said second light emitting diode being optically and electrically connected to the input of said amplifier, whereby the current through said second resistor is the current through said second light emitting diode, and when said output of said first and second light responsive means are equal, then the voltage drop across said first and second resistors are equal.

Claim 10

An optically coupled linear isolator as claimed in claim 7 in which, said output voltage comprising the voltage across said output power supply and the output of said second amplifier means.

Claim 13

The method as claimed in claim 9 including the step of, driving said signals applied to said first and second light emitting diodes to the linear response portion of said light emitting diodes.

Claim 16

The method as claimed in claim 11 including the steps of, feeding the error signal through a resistance to the input of a second amplifier which amplifies the signal and applies the signal to the second light emitting diode, the other side of said second amplifier being supplied from power sources that have an electrically ground earth reference, and setting said system whereby the drops across said respective resistors are equal when said error signal is at zero voltage.